The Division of Comparative Medicine (DCM) is the sole centralized animal resource core facility at Georgetown University. The mission of the facility is to provide optimal husbandry and veterinary care, specialized technical support and appropriate regulatory oversight for research studies involving laboratory animals. The 50,740 sq. foot facility actively supports 133 research investigators with 218 animal care and use protocols. The building is comprised of 2 wings - the "Grey" Side and the "Blue" Side, constructed in 1986 and 1995, respectively. Fifty-seven investigators house animals on the Grey Side and utilize research support spaces. In 2006, the University initiated a 3-phase, 5 year plan to replace the 23 year old mechanical systems on the Grey Side. Two NCRR G20 grant projects are currently underway to complete the first 2 planned phases including the replacement of non-operational humidifiers;aged exhaust fans, cage wash equipment and the building management system;and upgrade of the dedicated cage wash facility HV system. This proposal seeks to complete Phase 3 of the institutional long range plan by replacement of 3 air handling units (AHUs) and associated mechanical support equipment. "In-kind" equipment replacement is requested, with all work performed solely in mechanical spaces (4,072 sf). Redundancy of the existing AHUs will allow phased replacement with minimal disruption of ventilation and ongoing research studies. This project embraces sustainable design principles consistent with LEED criteria. American jobs (15-23 FTE) would be maintained during the 21 month project period. Ten additional full time DCM jobs would be maintained after renovation. Mechanical systems renovation on the Grey Side of the resource core facility is critical to maintain the animal research program at Georgetown University. Optimal ventilation and proper sanitation of equipment/facilities safeguard animal health and support the conduct of PHS and other extramural supported research. If these mechanical systems fail, the institution risks the loss of irreplaceable animal models, 57 funded research programs, AAALACi accreditation and USDA registration.